src: use uv_async_t for WeakRefs

Schedule a task on the main event loop, similar to what the HTML
spec recommends for browsers.

Alternative to https://github.com/nodejs/node/pull/30198

PR-URL: https://github.com/nodejs/node/pull/30616
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

3 files changed, 30 insertions, 6 deletions

diff --git a/src/env-inl.h b/src/env-inl.h
index 15b5010deb..d34bd03c7c 100644
--- a/src/env-inl.h
+++ b/src/env-inl.h
@@ -1118,6 +1118,7 @@ void Environment::RemoveCleanupHook(void (*fn)(void*), void* arg) {
 inline void Environment::RegisterFinalizationGroupForCleanup(
     v8::Local<v8::FinalizationGroup> group) {
   cleanup_finalization_groups_.emplace_back(isolate(), group);
+  uv_async_send(&cleanup_finalization_groups_async_);
 }
 
 size_t CleanupHookCallback::Hash::operator()(
diff --git a/src/env.cc b/src/env.cc
index 7f7c51c13c..dc99e4bd53 100644
--- a/src/env.cc
+++ b/src/env.cc
@@ -459,8 +459,17 @@ void Environment::InitializeLibuv(bool start_profiler_idle_notifier) {
   // will be recorded with state=IDLE.
   uv_prepare_init(event_loop(), &idle_prepare_handle_);
   uv_check_init(event_loop(), &idle_check_handle_);
+  uv_async_init(
+      event_loop(),
+      &cleanup_finalization_groups_async_,
+      [](uv_async_t* async) {
+        Environment* env = ContainerOf(
+            &Environment::cleanup_finalization_groups_async_, async);
+        env->CleanupFinalizationGroups();
+      });
   uv_unref(reinterpret_cast<uv_handle_t*>(&idle_prepare_handle_));
   uv_unref(reinterpret_cast<uv_handle_t*>(&idle_check_handle_));
+  uv_unref(reinterpret_cast<uv_handle_t*>(&cleanup_finalization_groups_async_));
 
   thread_stopper()->Install(
     this, static_cast<void*>(this), [](uv_async_t* handle) {
@@ -523,6 +532,10 @@ void Environment::RegisterHandleCleanups() {
       reinterpret_cast<uv_handle_t*>(&idle_check_handle_),
       close_and_finish,
       nullptr);
+  RegisterHandleCleanup(
+      reinterpret_cast<uv_handle_t*>(&cleanup_finalization_groups_async_),
+      close_and_finish,
+      nullptr);
 }
 
 void Environment::CleanupHandles() {
@@ -1046,19 +1059,27 @@ char* Environment::Reallocate(char* data, size_t old_size, size_t size) {
   return new_data;
 }
 
-bool Environment::RunWeakRefCleanup() {
+void Environment::RunWeakRefCleanup() {
   isolate()->ClearKeptObjects();
+}
 
-  while (!cleanup_finalization_groups_.empty()) {
+void Environment::CleanupFinalizationGroups() {
+  HandleScope handle_scope(isolate());
+  Context::Scope context_scope(context());
+  TryCatchScope try_catch(this);
+
+  while (!cleanup_finalization_groups_.empty() && can_call_into_js()) {
     Local<FinalizationGroup> fg =
         cleanup_finalization_groups_.front().Get(isolate());
     cleanup_finalization_groups_.pop_front();
     if (!FinalizationGroup::Cleanup(fg).FromMaybe(false)) {
-      return false;
+      if (try_catch.HasCaught() && !try_catch.HasTerminated())
+        errors::TriggerUncaughtException(isolate(), try_catch);
+      // Re-schedule the execution of the remainder of the queue.
+      uv_async_send(&cleanup_finalization_groups_async_);
+      return;
     }
   }
-
-  return true;
 }
 
 void AsyncRequest::Install(Environment* env, void* data, uv_async_cb target) {
diff --git a/src/env.h b/src/env.h
index 78724cebc1..c0c8ac0db4 100644
--- a/src/env.h
+++ b/src/env.h
@@ -1128,7 +1128,8 @@ class Environment : public MemoryRetainer {
   void RunAtExitCallbacks();
 
   void RegisterFinalizationGroupForCleanup(v8::Local<v8::FinalizationGroup> fg);
-  bool RunWeakRefCleanup();
+  void RunWeakRefCleanup();
+  void CleanupFinalizationGroups();
 
   // Strings and private symbols are shared across shared contexts
   // The getters simply proxy to the per-isolate primitive.
@@ -1270,6 +1271,7 @@ class Environment : public MemoryRetainer {
   uv_idle_t immediate_idle_handle_;
   uv_prepare_t idle_prepare_handle_;
   uv_check_t idle_check_handle_;
+  uv_async_t cleanup_finalization_groups_async_;
   bool profiler_idle_notifier_started_ = false;
 
   AsyncHooks async_hooks_;